Reference is made to applicant's co-pending application Serial No. 952,574, filed Oct. 18, 1978 on SNOW SCOOP. This invention belongs to the field of snow removal devices such as snow scoops and shovels. These conventionally are made of aluminum with a steel wear strip attached, as by riveting in a separate manufacturing step, along the leading edge portion.
An ideal material for snow scoops and shovels is high density polyethylene or an equivalent plastic. It is light in weight and snow will not stick to it.
To minimize manufacturing costs, it would be preferable to attach a steel wear strip automatically during molding of the plastic.
A problem however arises from the mold shrinkage properties of plastics materials. For high density polyethylene, this is in the neighborhood of 0.02 inches per inch. This means, for a snow scoop 24 inches wide, with a steel wear strip extending along the leading edge portion, the plastic material will shrink almost half an inch in cooling down from the mold, while the steel wear strip for all practical purposes would not shrink at all. This differential shrinkage creates a very serious problem of attaching a non-shrinkable wear strip to a shrinkable plastic leading edge portion before the latter has cooled and the mold shrinkage runs its course. Some previous attempts to mold the plastic while hot directly to a steel wear strip have resulted in cracking of the plastic or distortion and bowing of the leading edge portion because of this vast difference in shrinkage.